Molding apparatus

ABSTRACT

Apparatus for dry pressing and isostatic pressing of ceramic powder to form pipe wherein a groove is provided near a pipe end by means of arcuate, metallic segments which are hydraulically pressed into the powder by flexible tooling. The adjacent portion of the pipe is formed by a punch.

United States Patent [56] References Cited UNITED STATES PATENTS [72] Inventor DavidG.Loom1s 217 Gypsy Lane, Wynnewood, Pa. 19096 mm m m m m .L tfly n... n rw m W m mom Mk a e Tmnhm n e rmdceo ma .Ee n n wwwdflmewa i i SsGDTLwPHL 8234455579 5666666666 9999999999 1111111111 ////l///// 2523237997 1 l 1 5 67630207 09553502 9 u m 3444 236 4 63 2679045 2333333333 0 N mm M m n a b m! H w W0 n M5 6 "9 a1 #1 8 .m 2m 1 9 8 6 u 0 with t. v Ph 3 7 u 7 .CS 0. d N. m d ne .13 AF? 11] 224 [Ill 9 09 99 UOl/l l/U 0/500- 85 2 1921/1 5/4 00 H 8 2 .1 8 1M 1 L J m m a W OS m M "7w .mm mm 5, We an mm rt PA 8 m HF 8 .m PW P n D M8 5 mm C M3 H U [52] US. 18/5 HA,

18/D1G. 26, l8/DIG. 44, l8/D1G. 19, 25/45 ABSTRACT: Apparatus for dry pressing and isostatic pressing in a groove is provided 1330b 5/02, Bb 1 1/00 Int. of ceramic powder to form pipe where near a pipe end by means of arcuate, metallic segments which are hydraulically pressed into the powder by flexible toolin The adjacent portion of the pipe is formed by a punch.

[] Field of 25/45, 39; 18/5, 5 H, D16. 44, DlCv. 26', 249/98,

PATENTEU JUL20 I971 SHEET 1 OF 6 INVENTOR.

B BY DAVID G. LOOMIS FIG. I My ATTORNEY PATENTEflJuLaolsn 3 593373 sum 2 or 6 DAVID G. LOOMI INVEN FIG.3 BY I ATTORNEY PATENTED JUL20I97I 3,593; 373

sum 3 UF 6 INVENTOR. DAVID G. LOOMIS BY M M ATTORNEY 0 nFk n FIG. 4

PATENTEU JULZOIQYI 3583; 373

SHEET 5 OF 6 INVENTOR. DAV'D G. LOOMIS BY ATTORNEY FIG; 6

PATENYEU JUL20 i971 SHEEI 8 UF 6 m H U kym vw//////////////// 7 %Z FIG. 8

INVENTOR. DAVID G. LOOMIS BY W WW ATTORNEY MOLDING APPARATUS CROSS-REFERENCES TO RELATED APPLICATIONS This application is a continuation-in-part of applicant-s prior copending application bearing .Ser. No. 513,440 filed Dec. 13, I965 andzthereafter abandoned- BACKGROUND OF-THEEINVENTION 1. Field of the Invention This invention relates generally to the art ofzcompacting pelletized or powdered materials,1such.asceramic-or metallic pellets or powders, wherelthe hydraulicpressureof aliquid, such as oil or .water,'is exerted upon a flexible bag enclosing the pelletized or powderedmaterials and-serving'as a mold. The invention is particularly concerned withzanapparatusfor molding pipe composed of clay or other ceramic substance.

2. Description of the Prior Art 1 Heretofore, pipehas been-produced bypressingqsemidry mixtures of powdered or pelletizedmaterialin molds or bags composed of rubber, which are disposed in metal chambers and there subjectedto high hydraulic pressure by means of suitable pumps. However, this method hasencountered substantial difficulties where it has been desired-to produce piping I having annular grooves and otherelements intended for service as partof a pipe joint such asthatof bell and spigot piping. Thus, by conventional methods, ithas been difficult to compact pipe having bell portionsland annular grooves, such as O-ring grooves, formed to closectolerances. Moreoveryit has also been difficult by conventionalxmethods to compact pipe having very smoothly flnished-insidebores andrequiring.

a minimum of subsequent finishingoperations.

The present invention overcomes these difficultiesbMore specifically, it is an object of the present invention toprovide A still further object of the invention is to provide an ime proved and economical means for compacting sewer pipe.

Other objects and advantages of the present invention will become apparent from the following discussion as read in connection with the accompanying drawings.

SUMMARY OF TI-IEI-N-VENTION In the present invention, a ceramic. pipe is formed-in a bag mold by simultaneous dry pressingand'isostatic pressing of a suitable powder orpelletized materialpAnannular grooveis means for forming annular grooves within-closetolerances provided on the external surface of thepipeby means ofa seg mented, retractable, arcuate die within .said mold, the 'die" being-urged by hydraulic pressure into the-surface of the pipe during the aforesaidpressing operationwhile the powdered or pelletizedmaterial-is surmounted by a hard, metallic'punch' which forms an end face on the piperThe tolerances of the annulargroove, end-face and adjacent surfaces are determined by the tolerances'of the segmented die and punch.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings: 7 FIG. I is a fragmentary cross-sectional'elevational view depicting one embodiment of the presentinvention;

FIG. 2 is a fragmentary plan view taken about the line 2-2' of FIG. 1;

FIG. 3 is across-sectional view taken about the line 3-3 of FIG. 1;

FIGS. 4, 5, 6, 7 and 8-are fragmentary cross-sectional elevations depicting'various steps wherein the aforesaid embodiment of the present invention is employedin the production of pipe.

Throughout the various -views,- similar numerals are employed to designate similar partsof the said embodiment of the invention.=

. DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is intended for use in a suitable hydraulic pressure chamber, such'as is well known to those skilled in the art and may be employed in connection with the molds known'as wet bag tooling in the'manner hereinafter described. However, it is to be understood that the invention may also be employed with molds known as dry bag tooling.

As may be seen in FIGS. 1 and 2 of the accompanying drawings, one embodiment of the invention comprises a cylindrical housing 10 provided with upper and lower cover rings ll, 12 depending from said housing'10. The lower cover ring 12, is threadedly engaged witha suitable plug 13; and the upper cover ring 11 is threadedly engaged with a suitable plug, generally designated by the numeral 14.

The plug l4'includesa sleeve '15 'threadedly engagedwith the upper 'coverring- ILA-collar l6is housed within the sleeve 15 and is'abuttableagainsta shoulder 18 formed upon the intemal'periphery of the sleeve 15:Said collar 16' is also threadedly engaged with a generally cylindrical 'cap 19 which is provided with an air valve 20.

A hollow, cylindrical punch 21, composed of a hard material such as a suitable metal or otherinflexible substance,is

slidably engaged with'the cap l9, the mating parts of these I9QTh'e punch 21 is also slidably engaged with a cylindrical core pin 24 whichsurmounts the plug 13.

As maybe seen in FIG. I, the core pin 24 is surrounded by a region 25 adapted to-receive'a quantity of powdered or pelletizedmaterial intended tobe compacted or pressed into the form of 'a pipe. Said region 25 is, in turn, enclosed in a generally'cylindrical bag'26 composed of rubber or other suitably flexible material, bag 26' being, in turn, received within a suitable, flexible cylinder such as that formed "by cylindrical bags27 and 28, both'of'which are also composed of rubber or other suitably flexible material.

The housing l0is provided with suitable apertures, such as aperture29 through-which a hydraulic pressure maybe communicated by a fluid contactable withbag 28 and thence to bags 27and 26,- thereby exerting a hydraulic pressure upon the powdered or pelletized material received within the region 25.

Thus, it will be seen that such pressure can be employed to compact hollow cylindrical objects such'as piping formed of clay or other ceramic material.

An important feature of the present invention resides in its" provision for forming the end portions of such piping; and this feature may be'better understood from a description of the steps employed in compacting a pipe, such as a ceramic sewer .pipe, and various elements of the present invention'associated compacted into the form of a sewer pipe of conventional bell and spigot design. Said material 30 is loaded into region'25' until the material reaches the level indicated by the numeral 31.

During this loading operation, the above-described housing 10 and its contents may be disposed upon a jolter or other suitable vibratory mechanism so as to densify the said powdered or pelletized material 30 in the conventional manner.

As shown in FIG. 4, after loading, as aforesaid, the punch 21 is disposed in a closed position with respect to the cap 19 and core pin 24 but said punch 21 is in a spaced relation with respect to the material 30, thereby defining a spaced region 32.

Said region 32 communicates with a radial channel 33 which, in turn, intersects with a vertical channel 34 communicatin g with the air valve 20.

After the punch 21 is disposed as depicted in FIG. 4, the air valve 20 is adjusted, as by partially unscrewing it, so as to cause it to occupy a spaced relation with respect to its seat 35, this disposition of the air valve 20 corresponding with an open position thereof wherein air may be communicated from the spaced region 32 through the channels 33, 34 and into the valve bore 36. Thus, the air valve 20 may be connected to a suitable pump or other exhaust means whereby air in spaced region 32 may be evacuated, as desired. So, also, any air or other gas or vapor which may be entrapped within the powdered or pelletized material 30 would, by virtue of such evacuation, tend to be drawn into the region 32 and thence exhausted therefrom.

When such evacuation has been completed, the air valve 20 is tightened, as by screwing it into contact with its seat 35, thereby shutting the valve 20. Then, the complete assembly, i.e., the housing and all of the above-described contents are disposed within a suitable hydraulic pressure chamber which is preferably of the type known in the art as an isostatic chamber. Such chamber is then closed and the hydraulic fluid therein subjected to a suitable pressure in the conventional manner, thereby transmitting such pressure through each aperture 29 to the bags, 28, 27, 26 disposed within the housing 10. The bags, 28, 27, 26, in turn, communicate the hydraulic pressure to the powdered or pelletized material 30, thereby pressing it to conform with the internal periphery of the bag 26 and the external periphery of the core pin 24, as is depicted in FIG. 5 of the drawings. In this way, the said material 30 is compacted to form a pipe as defined by the bag 26 and core pin 24.

It is also to be noted that at the same time that the said bags 28, 27, 26 are subjected to hydraulic pressure, that pressure also acts upon the punch 24 so as to depress it against the upper end of the material 30, thereby forming upon said pipe an end face 38, the surface of which conforms to the lower surface 39 ofthe punch 24. Thus, the precision with which the end face 38 is molded will be determined by the precision with which surface 39 is made; and in this way, by using a surface 39 machined within close tolerances, the end face 38 will be formed with correspondingly close tolerances.

A similar situation prevails at the lower end of the pipe where the powdered or pelletized material 30 is compacted against a precisely formed boss, generally designated by the numeral 40 and including an upper face 41 and circumferential periphery 42 which define the internal periphery ofa bell-shaped end of said pipe. As in the case of end face 38, the boss 40 can be machined to close tolerances, thereby imparting correspondingly close tolerances to the internal periphery ofthe bell-shaped pipe end.

An important feature of the present invention resides in the means for imparting an annular groove 47 to the upper end or spigot of the pipe thus molded. Thus, the cylindrical cap 19 includes a base 43 having a threaded counterbore or recess 44. This recess 44 is threadedly engaged with an annular retaining ring 45 which is preferably provided with a plurality of pins or detents 46 threadedly engaged with radial apertures 48 provided in said retaining ring 45 at equal angular intervals.

The pins or detents 46 are abuttable against an annular die, generally designated by the numeral 49 and including a plurality of arcuate segments 50. The internal periphery of the annular die 49 includes an inclined, external, circumferential peripheral surface 37 abutting against an inclined seat 57 provided on the lower surface of the annular retaining ring 45.

The annular die 49 is also provided with upper and lower circumferential peripheral surfaces 51, 52 and an intermediate circumferential surface 53 having a reduced internal diameter corresponding with the depth of the annular groove to be imparted to the spigot. Said intermediate circumferential surface 53 also terminates in upper and lower horizontal shoulders 54, 55 which correspond with the sidewalls of the annular groove to be formed on the spigot.

It will be seen that the pins or detents 46 may be adjusted as desired so as to insure an accurate alignment of the die segments 50 and since said segments can be machined within close tolerances, a corresponding precision can be imparted to the annular groove 47 formed on the spigot. Similarly, the upper and lower surfaces 56, 58 adjacent to the groove 47 may also be molded with great precision corresponding to the accuracy with which the mating surfaces of the segments 50 are formed.

After the material 30 has been compacted so as to assume the form of a bell and spigot pipe as aforesaid, the hydraulic pressure in the chamber is reduced so as to permit the chamber to be opened and the housing 10 to be opened and the housing 10 to be removed therefrom. Then the air valve 20 is unscrewed so as to break the vacuum within the mold, thereby permitting the bags 26, 27, 28 to return to the position which they occupied prior to their subjection to the aforesaid hydraulic pressure, as shown in FIG. 6. The pipe 60 formed by said pressure, retains its compacted shape, thereby determining a spaced region 61 surrounding the circumferential periphery of the portion of the pipe 60 below its spigot end. Thus, the innermost bag 26 is released from contact with the pipe 60 when the hydraulic pressure is released.

The mold may then be opened by removing the punch 21, cap 19, collar 16, sleeve 15, the disposition of the mold with these parts removed being depicted in FIG. 7. Then, the retaining ring and segments may also be removed. As depicted in FIG. 8, this arrangement permits the compacted pipe to be raised so that its bell end abuts against the lower inclined surface 65 of the bag 26, thereby urging said bag 26 to withdraw from the mold together with the pipe 60. When such withdrawal is accomplished, the pipe 60 can be separated from the bag 26 and the mold be reassembled to assume the disposition depicted in FIG. 1, wherein the aforesaid operations may be repeated to form further bell and spigot piping, as desired. It may be added that in the course of such withdrawal, the pipe 60 can be separated from the core pin while the latter is within the mold or said core pin can be removed with the pipe 60 and thereafter separated therefrom, as is convenient.

From the foregoing, it will be seen that the objects of the invention have been achieved in a simple but ingenious manner. Thus, the annular groove, formed on the external circumferential periphery of the spigot, may be made very precisely, thereby permitting such annular groove to serve as an O-ring groove constituting part of a bell and spigot joint. So, also, since the bell, as well as the spigot portions of the joint, may be formed as described above, within close tolerances, the seal accomplished by such joint will be highly efficient and the joint itself may be of minimum size, i.e., the clearance between the adjacent spigot and bell in such a joint may be minimized by reason of the great precision of manufacture attainable by this invention.

It will also be seen that both internal and external surfaces of such bell and spigot portions of pipe may be produced with a smooth finish and, by virtue of the aforesaid precision of manufacture, will require little or no subsequent finishing. Moreover, by reason of the above-described advantages, the production of piping by this invention is attendant with economies not available in conventional procedures and apparatus.

The embodiment of the invention illustrated and described hereinabove has been selected for the purpose of clearly setting forth the principles involved. It will be apparent, however, that the present invention is susceptible to being modified in respect to details of construction, combination and arrangement of parts which may be resorted to without departure from the spirit and scope of the' invention as claimed.

lclaim:

1. In amold disposable within a hydraulic fluid and including a housing provided with at least one aperture for reception of said fluid, opposing end cover means accommodating therebetween a dry powdered material intended to be pressed into cylindrical form and flexible means communicating with said fluid and urging said powdered material to assume said cylindrical form when said fluid is subjected to pressure, the combination comprising:

a. an annular die including a plurality of arcuate segments communicating with the external periphery of said powdered material and having an internal diameter which is smaller than the external diameter of adjacent portions of said powdered material, thereby forming an annular groove in said powdered material;

b. means for supporting said annular die in circular alignment;

c. said supporting means depending from said cover means;

(1. said supporting means including:

i. an annular retaining ring provided with an inclined seat formed on the lower surface thereof and a plurality of radially disposed apertures;

ii. a plurality of pins adjustably secured within said apertures;

iii. said pins being abuttable against the arcuate segments to urge them into circular alignment;

iv. said arcuate segments also being abuttable against said inclined seat.

2. in a device according to claim I,

a. said end cover means including a cap provided with a base having a recess;

b. said annular retaining ring being engaged with the periphery of said recess.

3. In a device according to claim 2, said end cover means including:

a. an axial aperture;

b. a punch slidably received within said axial aperture;

c. a portion of said punch being communicable with said hydraulic fluid, whereby said punch is urged into the mold when such fluid is subjected to pressure;

d. another portion of said punch being abuttable against said powdered material, whereby said pressure is transmissable to an end surface of said powdered material. 

2. In a device according to claim 1, a. said end cover means including a cap provided with a base having a recess; b. said annular retaining ring being engaged with the periphery of said recess.
 3. In a device according to claim 2, said end cover means including: a. an axial aperture; b. a punch slidably received within said axial aperture; c. a portion of said punch being communicable with said hydraulic fluid, whereby said punch is urged into the mold when such fluid is subjected to pressure; d. another portion of said punch being abuttable against said powdered material, whereby said pressure is transmissable to an end surface of said powdered material. 